I used a wedge style scanner and wrote the code behind the app that took the barcode and looked up the product information. It wasn't hard to write but belongs to a company so I can't share it.
If you can't code, then most end up buying what they want.
-> Amazon at one time had a phone that did something like you asked for. Maybe their app does this?
Ok been trying to find a good app that I can scan barcodes, that will pop up info on the product ratings on it and similar products and there ratings. Dose such a thing exist? When I google it a bunch of crap paid promotion sites seem to be all that come up.